The invention relates to a signal transmission system comprising a transmitter, a receiver, and a transmission link in which the signal to be transmitted is pulse code modulated.
Transmission systems for digitized voice signals commonly employ either delta modulation or pulse code modulation. Radio links frequently use delta modulation because of the relative simplicity of the equipment required and because of its immunity to the effects of interference. The greater noise immunity of a delta modulated signal compared with that of a pulse code modulated signal arises because, for delta modulation, all bits are of equal significance whereas for pulse code modulation some bits are of critical importance, for example the sign bit.